KR102887104B1 - Apparatus of light source with near infrared laser and substrate inspection system inculding the same - Google Patents

Abstract

A lighting device using a near-infrared laser is disclosed, comprising: a near-infrared laser that outputs laser light; a multi-mode optical fiber that internally reflects the laser light and outputs it in a first shape; and an optical fiber bundle that focuses the laser light output in the first shape and outputs it in a second shape that is more diffuse than the first shape.

Description

{APPARATUS OF LIGHT SOURCE WITH NEAR INFRARED LASER AND SUBSTRATE INSPECTION SYSTEM INCULDING THE SAME}

The present disclosure relates to a lighting source, and more particularly, to a lighting device using a near-infrared laser and a substrate inspection system including the same.

NAND is a non-volatile memory type that does not require power to maintain stored data. With the growing demand for consumer electronics, cloud computing, and big data, the demand for higher-capacity and better-performing NAND memory continues to grow. As conventional two-dimensional (2D) NAND memory approaches its physical limits, three-dimensional (3D) NAND memory is playing a crucial role. 3D NAND memory utilizes multiple stacked layers on a single chip to achieve higher density, higher capacity, faster performance, lower power consumption, and better cost efficiency.

Meanwhile, defects on the surface of semiconductor wafers or semiconductor devices can impact the reliability and yield of these devices. Therefore, various non-destructive defect detection methods utilizing light are being used to detect these defects.

Typically, a DUV laser is used as a light source in a defect inspection system for semiconductor wafers. However, since the DUV laser light source can only reach a depth of about 10 μm, there is a limitation in detecting defects at a depth of several tens of μm in comparison to the stacked structure of 3D NAND memory.

Korean Patent No. 10-2357638 (January 28, 2022)

The purpose of the embodiment disclosed in the present disclosure is to provide an illumination device that outputs illumination light from a near-infrared laser by arranging a multi-mode optical fiber and an optical fiber bundle, and a substrate inspection system including the same.

The problems to be solved by the present disclosure are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

A lighting device according to the present disclosure for achieving the above-described technical task includes: a near-infrared laser that outputs laser light; a multi-mode optical fiber that internally totally reflects the laser light and outputs it in a first shape; and an optical fiber bundle that focuses the laser light output in the first shape and outputs it in a second shape that is more spread out than the first shape.

Meanwhile, the present invention may further include a diffuser provided between the multi-mode optical fiber and the optical fiber bundle, and uniformly diffusing the laser light output in the first form and providing it to the optical fiber bundle.

In addition, an attenuator provided between the near-infrared laser and the multi-mode optical fiber and controlling the output of the laser light and providing it to the multi-mode optical fiber may be further included.

In addition, the first form may be a form in which the beam quality (M ² ) value of the laser light is increased.

Additionally, the second form may be a form in which the coherence of the laser light is broken.

A substrate inspection system according to the present disclosure comprises: a stage for receiving a substrate; an image sensor for acquiring an image of the substrate; and an illumination device for providing illumination light to the substrate; wherein the illumination device comprises: a near-infrared laser for outputting laser light; a multi-mode optical fiber for internally totally reflecting the laser light and outputting it in a first shape; and an optical fiber bundle for focusing the laser light output in the first shape and outputting it in a second shape that is more diffuse than the first shape.

Meanwhile, the lighting device may further include a diffuser provided between the multi-mode optical fiber and the optical fiber bundle, and uniformly diffusing the laser light output in the first form and providing it to the optical fiber bundle.

In addition, the lighting device may further include an attenuator provided between the near-infrared laser and the multi-mode optical fiber, and controlling the output of the laser light and providing it to the multi-mode optical fiber.

In addition, the method may further include a deformation window that changes the spatial phase pattern of the laser light output from the optical fiber bundle and provides it to the substrate according to the type of defect structure of the substrate.

In addition, the method may further include an imaging optical system provided between the stage and the image sensor, which projects an image of the substrate onto the image sensor using the illumination light.

According to the aforementioned problem solving means of the present disclosure, a near-infrared laser light can be used as illumination. When such illumination light is applied to a substrate inspection device, defects of several tens of nm or less within a wafer can be detected, thereby overcoming the limitations of the lower layer inspection of a wafer using a substrate inspection device using existing DUV (Deep Ultraviolet) illumination light.

The effects of the present disclosure are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description below.

FIG. 1 is a drawing showing a lighting device using a near-infrared laser according to one embodiment of the present disclosure.
Figure 2 is an example of the output spectrum of laser light output from the near-infrared laser illustrated in Figure 1.
Figure 3 is a drawing showing the shape of laser light observed at each point in Figure 1.
FIG. 4 is a drawing showing a substrate inspection system according to one embodiment of the present disclosure.
FIG. 5 is a drawing showing a substrate inspection system according to another embodiment of the present disclosure.

Throughout this disclosure, the same reference numerals denote the same components. This disclosure does not describe all elements of the embodiments, and any content that is common in the technical field to which this disclosure pertains or that overlaps between embodiments is omitted. The terms "part, module, element, block" used in the specification may be implemented in software or hardware, and depending on the embodiments, multiple "parts, modules, elements, blocks" may be implemented as a single component, or a single "part, module, element, block" may include multiple components.

Throughout the specification, when a part is said to be "connected" to another part, this includes not only direct connection but also indirect connection, and indirect connection includes connection via a wireless communication network.

Additionally, when a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

Throughout the specification, when we say that an element is "on" another element, this includes not only cases where the element is in contact with the other element, but also cases where another element exists between the two elements.

The terms first, second, etc. are used to distinguish one component from another, and the components are not limited by the aforementioned terms.

Singular expressions include plural expressions unless the context clearly indicates otherwise.

The identification codes for each step are used for convenience of explanation and do not describe the order of each step. Each step may be performed in a different order than specified unless the context clearly indicates a specific order.

The operating principle and embodiments of the present disclosure are described below with reference to the attached drawings.

As used herein, the term "device according to the present disclosure" encompasses a variety of devices capable of performing computational processing and providing results to a user. For example, the device according to the present disclosure may include a computer, a server device, and a portable terminal, or may be any one of them.

Here, the computer may include, for example, a notebook, desktop, laptop, tablet PC, slate PC, etc. equipped with a web browser.

The above server device is a server that processes information by communicating with an external device, and may include an application server, a computing server, a database server, a file server, a game server, a mail server, a proxy server, and a web server.

The above portable terminal may include, for example, a wireless communication device that ensures portability and mobility, and may include all kinds of handheld-based wireless communication devices such as a PCS (Personal Communication System), GSM (Global System for Mobile communications), PDC (Personal Digital Cellular), PHS (Personal Handyphone System), PDA (Personal Digital Assistant), IMT (International Mobile Telecommunication)-2000, CDMA (Code Division Multiple Access)-2000, W-CDMA (W-Code Division Multiple Access), WiBro (Wireless Broadband Internet) terminal, a smart phone, and a wearable device such as a watch, a ring, a bracelet, an anklet, a necklace, glasses, contact lenses, or a head-mounted device (HMD).

The artificial intelligence-related functions according to the present disclosure are operated via a processor and memory. The processor may be comprised of one or more processors. In this case, one or more processors may be a general-purpose processor such as a CPU, an AP, a Digital Signal Processor (DSP), a graphics-only processor such as a GPU or a Vision Processing Unit (VPU), or an artificial intelligence-only processor such as an NPU. One or more processors control the processing of input data according to predefined operating rules or artificial intelligence models stored in memory. Alternatively, if one or more processors are artificial intelligence-only processors, the artificial intelligence-only processor may be designed with a hardware structure specialized for processing a specific artificial intelligence model.

FIG. 1 is a drawing showing a lighting device using a near-infrared laser according to one embodiment of the present disclosure.

Referring to FIG. 1, a lighting device (10) according to one embodiment of the present disclosure may include a near-infrared laser (11), an attenuator (13), a multi-mode fiber (MMF) (15), a diffuser (17), and fiber bundles (19).

A near-infrared laser (11) can output laser light.

For example, the near-infrared laser (11) can output near-infrared laser light, and preferably can output near-infrared pulse laser light that is variable in a wavelength band of about 600 nm to 900 nm.

Figure 2 is an example of the output spectrum of laser light output from the near-infrared laser illustrated in Figure 1.

Referring to FIG. 2, the near-infrared laser (11) has a wavelength variable range of 650 nm to 950 nm and can output laser light having a wavelength width (FWHM) of 1 nm or less.

The attenuator (13) can control the output intensity of laser light output from the near-infrared laser (11).

For example, the attenuator (13) can reduce the output intensity by selectively reflecting or transmitting the laser light output from the near-infrared laser (11) according to the polarization state of the laser light, including a polarizing beam splitter (PBS).

An attenuator (13) can be provided between a near-infrared laser (11) and a multi-mode optical fiber (15), and can control the output intensity of laser light output from the near-infrared laser (11) and provide it to the multi-mode optical fiber (15).

Meanwhile, a lighting device (10) according to one embodiment of the present disclosure may further include a plurality of mirrors for directing laser light output from a near-infrared laser (11) to an attenuator (13) as illustrated in FIG. 1.

In addition, the lighting device (10) according to one embodiment of the present disclosure may further include at least one lens for focusing the laser light output from the attenuator (13) onto a multi-mode optical fiber (15) as illustrated in FIG. 1.

A multi-mode optical fiber (15) can output laser light output from a near-infrared laser (11) in a first form by internally totally reflecting the light.

A multi-mode optical fiber (15) transmits light through multiple paths, and at this time, as total reflection is repeated, the light may appear in a diffused or blurred form through multiple paths. For example, the beam quality (M ² ) value of laser light output from a near-infrared laser (11) and transmitted through an attenuator (13) may be 1.0, and when such laser light passes through a multi-mode optical fiber (15), the beam quality (M ² ) value may increase to 50 or more. That is, the first form may be a form in which the laser light is diffused, and may be a form in which the beam quality (M ² ) value increases.

In this embodiment, the diameter of the multi-mode optical fiber (15) is 500 um or more, and the NA can be implemented as 0.22.

The optical fiber bundle (19) can focus the first type of laser light output from the multi-mode optical fiber (15) and output it in a second type that is more spread out than the first type.

The optical fiber bundle (19) corresponds to a bundle of multiple single optical fibers, and can output laser light in a diffused form due to path differences and interference between the multiple optical fibers. For example, laser light passing through the optical fiber bundle (19) may be output in a form in which coherence is broken, and such laser light would be suitable for use as illumination. In other words, the second form may be a more diffuse form than the first form, and may be a form in which coherence is broken.

In this embodiment, the optical fiber bundle (19) can be implemented by weaving tens to thousands of single optical fibers.

Meanwhile, the first type of laser light output from the multi-mode optical fiber (15) can pass through the diffuser (17) and be provided to the optical fiber bundle (19).

The diffuser (17) can uniformly diffuse the first type of laser light output from the multi-mode optical fiber (15).

At least one diffuser (17) can be provided between the multi-mode optical fiber (15) and the optical fiber bundle (19), and can uniformly diffuse the first type of laser light output from the multi-mode optical fiber (15) and provide it to the optical fiber bundle (19).

Meanwhile, the lighting device (10) according to one embodiment of the present disclosure may further include at least one lens for focusing the laser light passing through the diffuser (17) into the optical fiber bundle (19) as illustrated in FIG. 1.

Figure 3 is a drawing showing the shape of laser light observed at each point in Figure 1.

Referring to (a) of FIG. 1 and FIG. 3, a Gaussian beam of laser light can be confirmed at the first point (P1) between the near-infrared laser (11) and the attenuator (13), and at this time, the beam quality (M ² ) of the laser light will be 1.0.

Referring to FIG. 1 and FIG. 3 (b), at the second point (P2) between the multi-mode optical fiber (15) and the diffuser (17), the Gaussian beam may exhibit a spread shape as it passes through the multi-mode optical fiber (15). That is, the laser light output from the near-infrared laser (11) will pass through the multi-mode optical fiber (15) and be output in the first shape with increased beam quality (M ² ).

Referring to (c) of FIG. 1 and FIG. 3, at the third point (P3) between the diffuser (17) and the optical fiber bundle (19), the first type of laser light output from the multi-mode optical fiber (15) can be uniformly diffused.

Referring to FIG. 1 and FIG. 3 (d), at the fourth point (P4) of the output end of the optical fiber bundle (19), the laser light may be more spread out than in the first form, showing a form in which the coherence is broken. In other words, the laser light passing through the optical fiber bundle (19) will be output in the second form in which the coherence is broken.

An illumination device (100) according to one embodiment of the present disclosure is configured so that laser light output from a near-infrared laser (11) can sequentially pass through a multi-mode optical fiber (15) and an optical fiber bundle (19), thereby outputting the laser light in a spread form, thereby enabling the use of the near-infrared laser light as illumination. When such illumination light is applied to a substrate inspection device, it is possible to detect defects of several tens of nm or less within the wafer, thereby overcoming the limitations of the inspection of the lower part of the wafer in a substrate inspection device using existing DUV (Deep Ultraviolet) illumination light.

FIG. 4 is a drawing showing a substrate inspection system according to one embodiment of the present disclosure.

Referring to FIG. 4, a substrate inspection system (100) according to one embodiment of the present disclosure adopts a dark field inspection method and may include a lighting device (10), a stage (30), an image sensor (50), and an imaging optical system (70).

The lighting device (10) is the lighting device (10) illustrated in FIG. 1, and can provide lighting light from a near-infrared laser.

A detailed description of the lighting device (10) will be replaced with the one described above.

The stage (30) can store a substrate.

In this embodiment, the substrate may be a 3D NAND semiconductor wafer.

For example, the stage (30) may be provided to be movable during the inspection or measurement process of the substrate by a predetermined control device.

Meanwhile, another substrate inspection system (100) according to one embodiment of the present disclosure may further include an objective lens disposed on a stage. The objective lens may magnify and project the substrate onto an image sensor (50).

Meanwhile, the substrate inspection system (100) according to one embodiment of the present disclosure adopts a dark field inspection method, so that the lighting device (10) can be positioned to provide lighting light to the side of the substrate stored on the stage (30).

The image sensor (50) can acquire an image of the substrate.

For example, the image sensor (50) may include a CCD (Charge Coupled Device) or CMOS image sensor, and may obtain an image detection signal of the substrate by receiving reflected light reflected from the substrate. The image sensor (50) may obtain an image of the substrate using the image detection signal of the substrate, and may analyze the image to inspect for defects in the substrate.

The optical system (70) is provided between the stage (30) and the image sensor (50), and can project an image of the substrate onto the image sensor (50) using illumination light provided from the illumination device (10).

For example, the imaging optical system (70) may include imaging relay lenses, an imaging polarizer, an imaging aperture, and an oculus lens. The imaging relay lenses may enable adjustment of the distance between the objective lens and the oculus lens. The imaging polarizer may polarize reflected light. The imaging aperture may define the beam size of the reflected light. The oculus lens may focus the reflected light onto an image sensor.

FIG. 5 is a drawing showing a substrate inspection system according to another embodiment of the present disclosure.

Referring to FIG. 5, a substrate inspection system (101) according to another embodiment of the present disclosure adopts a bright field inspection method and may include a lighting device (10), a stage (30), an image sensor (50), an imaging optical system (70), and a deformable window (90).

The lighting device (10) is the lighting device (10) illustrated in FIG. 1, and can provide lighting light from a near-infrared laser.

A detailed description of the lighting device (10) will be replaced with the one described above.

The stage (30) can store a substrate.

In this embodiment, the substrate may be a 3D NAND semiconductor wafer.

For example, the stage (30) may be provided to be movable during the inspection or measurement process of the substrate by a predetermined control device.

Meanwhile, another substrate inspection system (101) according to another embodiment of the present disclosure may further include an objective lens disposed on a stage. The objective lens may magnify and project the substrate onto an image sensor (50).

Meanwhile, a substrate inspection system (101) according to another embodiment of the present disclosure adopts a bright field inspection method, so that the lighting device (10) can be positioned to directly provide lighting light to a substrate stored on a stage (30).

The image sensor (50) can acquire an image of the substrate.

For example, the image sensor (50) may include a CCD (Charge Coupled Device) or CMOS image sensor, and may obtain an image detection signal of the substrate by receiving reflected light reflected from the substrate. The image sensor (50) may obtain an image of the substrate using the image detection signal of the substrate, and may analyze the image to inspect for defects in the substrate.

The optical system (70) is provided between the stage (30) and the image sensor (50), and can project an image of the substrate onto the image sensor (50) using illumination light provided from the illumination device (10).

For example, the imaging optical system (70) may include imaging relay lenses, an imaging polarizer, an imaging aperture, and an oculus lens. The imaging relay lenses may enable adjustment of the distance between the objective lens and the oculus lens. The imaging polarizer may polarize reflected light. The imaging aperture may define the beam size of the reflected light. The oculus lens may focus the reflected light onto an image sensor.

The deformation window (90) can change the spatial phase pattern of the illumination light output from the lighting device (10) and provide it to the substrate.

The deformation window (90) is configured so that a plurality of cells arranged in a grid shape can individually control the refractive index of the illumination light transmitted through the voltage, thereby changing the spatial phase pattern of the illumination light.

The deformation window (90) can change the spatial phase pattern of the illumination light depending on the type of defect structure of the substrate.

For example, a substrate inspection system (101) according to another embodiment of the present disclosure may further include a predetermined control device. The control device may control a deformation window (90) to change a spatial phase pattern of illumination light to inspect a defect structure of the substrate. For example, when there are four types of defect structures of the substrate, namely, Fume spout, W bridge, W residue, and Void, the control device may control the deformation window (90) to change a spatial phase pattern of illumination light to provide the light to the substrate so that each type of defect structure can be detected. Meanwhile, the control device may also control a wavelength of laser light output from a near-infrared laser (11) so that the defect structure of the substrate can be detected so as to be detected so as to be detected so as to be provided to the substrate.

Additionally, the deformation window (90) reduces the focal size of the illumination light on the objective lens through aberration correction, thereby enabling detection of small defects (e.g., nm units) on the substrate.

The substrate inspection system (100, 101) according to the present disclosure can also inspect for defects in the lower layer of the wafer by inspecting for defects in a 3D NAND semiconductor wafer using illumination light provided from a near-infrared laser.

Meanwhile, the disclosed embodiments may be implemented in the form of a recording medium storing computer-executable instructions. The instructions may be stored in the form of program code, and when executed by a processor, may generate program modules to perform the operations of the disclosed embodiments. The recording medium may be implemented as a computer-readable recording medium.

Computer-readable storage media include all types of storage media that store instructions that can be deciphered by a computer. Examples include read-only memory (ROM), random access memory (RAM), magnetic tape, magnetic disks, flash memory, and optical data storage devices.

The disclosed embodiments have been described with reference to the attached drawings as described above. Those skilled in the art will understand that the present disclosure can be implemented in forms other than the disclosed embodiments without altering the technical spirit or essential features of the present disclosure. The disclosed embodiments are illustrative and should not be construed as limiting.

10: Lighting device
11: Near-infrared laser
13: Attenuator
15: Multimode fiber
17: Diffuser
19: Fiber optic bundle
30: Stage
50: Image sensor
70: Focusing optical system
90: Transform window
100, 101: Board Inspection System

Claims (10)

A near-infrared laser that outputs laser light;
A multi-mode optical fiber that internally reflects the laser light and outputs it in a first form;
An optical fiber bundle that focuses the laser light output in the first form and outputs it in a second form that is more spread out than the first form;
A deformation window that changes the spatial phase pattern of the laser light output from the optical fiber bundle and provides it to a substrate, and performs aberration correction so that the focus size of the laser light is adjusted based on the defect size of the substrate; and
A control device that controls the deformation window and the near-infrared laser so that the spatial phase pattern and the wavelength of the laser light are adjusted based on the type of the defect structure of the substrate;
The above deformation window is,
A plurality of cells arranged in a grid shape change the spatial phase pattern of the laser light by adjusting the refractive index of the laser light transmitted therethrough.
The first form above is,
The beam quality (M ² ) value of the above laser light is increased,
The second form above is,
A lighting device using a near-infrared laser, wherein the coherence of the laser light is broken.
In the first paragraph,
A lighting device using a near-infrared laser, further comprising a diffuser provided between the multi-mode optical fiber and the optical fiber bundle, and uniformly diffusing the laser light output in the first form and providing it to the optical fiber bundle.
In the second paragraph,
A lighting device using a near-infrared laser, further comprising an attenuator provided between the near-infrared laser and the multi-mode optical fiber, and controlling the output of the laser light and providing it to the multi-mode optical fiber.


delete delete A stage for storing the substrate;
An image sensor for acquiring an image of the substrate; and
A lighting device that provides lighting light to the above substrate;
The above lighting device,
A near-infrared laser that outputs laser light;
A multi-mode optical fiber that internally reflects the laser light and outputs it in a first form;
An optical fiber bundle that focuses the laser light output in the first form and outputs it in a second form that is more spread out than the first form;
A deformation window that changes the spatial phase pattern of the laser light output from the optical fiber bundle and provides it to a substrate, and performs aberration correction so that the focus size of the laser light is adjusted based on the defect size of the substrate; and
A control device that controls the deformation window and the near-infrared laser so that the spatial phase pattern and the wavelength of the laser light are adjusted based on the type of the defect structure of the substrate;
The above deformation window is,
A plurality of cells arranged in a grid shape change the spatial phase pattern of the laser light by adjusting the refractive index of the laser light transmitted therethrough.
The first form above is,
The beam quality (M ² ) value of the above laser light is increased,
The second form above is,
A substrate inspection system in which the coherence of the laser light is broken.

In paragraph 6,
The above lighting device,
A substrate inspection system further comprising a diffuser provided between the multi-mode optical fiber and the optical fiber bundle, and uniformly diffusing the laser light output in the first form and providing it to the optical fiber bundle.
In paragraph 7,
The above lighting device,
A substrate inspection system further comprising an attenuator provided between the near-infrared laser and the multi-mode optical fiber, the attenuator controlling the output of the laser light and providing it to the multi-mode optical fiber.
delete In paragraph 6,
A substrate inspection system further comprising an imaging optical system provided between the stage and the image sensor, the imaging optical system projecting an image of the substrate onto the image sensor using the illumination light.